Total depth after etching is 8.536 um
Calculated remaining resist as 8.02um, indicating an erosion of 0.72um in 10 minutes of etching
This equates to an erosion rate of 72 nm/min
The etch depth of 0.52um in 10 mins indicates an etch rate of 52.0nm/min
The selectivity is therefore 0.72:1